Antennas are important components of Wireless Capsule Endoscope (WCE) that has been explored due to its non-invasive nature compare to the traditional endoscopy. The main challenges of these antennas include data rate of the telemetry system, miniaturizing the capsule, propagating efficiency of the antenna in the vicinity of human body. In this paper, a miniature Ultra-wideband (UWB) antenna is proposed and evaluated for WCE applications. The proposed antenna consists of slotted circular radiating patch having a sawtooth partial ground plane with 50 Ohm microstrip feed line. The substrate of the proposed antenna is chosen as Roger R03010. The bandwidth enhancement is achieved by proper selection of dimensions and positions of slots on the radiating patch and introducing a sawtooth partial ground plane. The in-body performances of the antenna are investigated inside a homogeneous human muscle layer. The antenna is able to achieve an impedance bandwidth of 1.84 GHz from 4.6554 GHz to 6.4953 GHz for return loss less than −10 dB with Omni-directional pattern. Maximum power of 44.2051 mW can be set as input to the proposed antenna in order to comply with the IEEE C95.1-2005 safety standards.